We are independent & ad-supported. We may earn a commission for purchases made through our links.
Advertiser Disclosure
Our website is an independent, advertising-supported platform. We provide our content free of charge to our readers, and to keep it that way, we rely on revenue generated through advertisements and affiliate partnerships. This means that when you click on certain links on our site and make a purchase, we may earn a commission. Learn more.
How We Make Money
We sustain our operations through affiliate commissions and advertising. If you click on an affiliate link and make a purchase, we may receive a commission from the merchant at no additional cost to you. We also display advertisements on our website, which help generate revenue to support our work and keep our content free for readers. Our editorial team operates independently of our advertising and affiliate partnerships to ensure that our content remains unbiased and focused on providing you with the best information and recommendations based on thorough research and honest evaluations. To remain transparent, we’ve provided a list of our current affiliate partners here.

What is a Lead Screw?

By Paul Scott
Updated May 17, 2024
Our promise to you
About Mechanics is dedicated to creating trustworthy, high-quality content that always prioritizes transparency, integrity, and inclusivity above all else. Our ensure that our content creation and review process includes rigorous fact-checking, evidence-based, and continual updates to ensure accuracy and reliability.

Our Promise to you

Founded in 2002, our company has been a trusted resource for readers seeking informative and engaging content. Our dedication to quality remains unwavering—and will never change. We follow a strict editorial policy, ensuring that our content is authored by highly qualified professionals and edited by subject matter experts. This guarantees that everything we publish is objective, accurate, and trustworthy.

Over the years, we've refined our approach to cover a wide range of topics, providing readers with reliable and practical advice to enhance their knowledge and skills. That's why millions of readers turn to us each year. Join us in celebrating the joy of learning, guided by standards you can trust.

Editorial Standards

At About Mechanics, we are committed to creating content that you can trust. Our editorial process is designed to ensure that every piece of content we publish is accurate, reliable, and informative.

Our team of experienced writers and editors follows a strict set of guidelines to ensure the highest quality content. We conduct thorough research, fact-check all information, and rely on credible sources to back up our claims. Our content is reviewed by subject-matter experts to ensure accuracy and clarity.

We believe in transparency and maintain editorial independence from our advertisers. Our team does not receive direct compensation from advertisers, allowing us to create unbiased content that prioritizes your interests.

A lead screw, or power screw as it is also known, is a threaded bar or rod that converts radial or rotational motion into linear or straight line motion. This is achieved by passing the threaded rod through a corresponding opposite thread cut into a movable work piece as is seen in bench vices and car jacks. When the lead screw is turned, the work piece will move up or down the threads depending on the direction of the screw. The main difference between a lead screw and a regular fastener such as a nut and bolt is that a lead screw’s thread is far coarser and typically square in profile to reduce friction.

This conversion of motion is simply demonstrated by screwing a cap onto a bottle. When tightened, the cap moves down the thread on the bottle until it is tight and then, when loosened, moves up the threads until it is removed. A bench vice, for example, consists of one movable and one static jaw. The moving jaw is equipped with a threaded hole through which the lead screw passes. The lead screw is then locked into place with a circlip on the static jaw or frame of the vice.

When the power screw is turned, the moving jaw will be advanced up the threaded bar until it is locked against the static jaw. When the screw is turned in the opposite direction the moving jaw will move in the opposite direction, opening the vice again. A "C" clamp works on the same principle except it is then the lead screw itself that moves backward and forwards to clamp a work piece. Either way, the lead screw is converting its axial rotation into a linear or back and forth motion.

Although a power screw works on the same principle as a simple nut and bolt, the threads used in both applications differ considerably. The screw thread on a bolt, for instance, is of a V profile and is cut with a fairly fine or dense thread pitch, i.e., number of threads per inch of bolt length. This arrangement increases the friction caused when the nut is turned along the bolt and aids in creating a very secure locking effect when the nut is fully tightened. The thread pitch on a lead screw is far coarser, i.e., less threads per inch of screw length, which creates less friction and allows for easier and quicker turning of the screw while still producing a secure grip when tightened. The thread profile of a power screw is also typically square which, although more expensive to machine, produces the highest efficiency level.

About Mechanics is dedicated to providing accurate and trustworthy information. We carefully select reputable sources and employ a rigorous fact-checking process to maintain the highest standards. To learn more about our commitment to accuracy, read our editorial process.
Discussion Comments
About Mechanics, in your inbox

Our latest articles, guides, and more, delivered daily.

About Mechanics, in your inbox

Our latest articles, guides, and more, delivered daily.